6. The UPDATE State

6. The UPDATE State

When the client issues the QUIT command from the TRANSACTION state,
the POP3 session enters the UPDATE state. (Note that if the client
issues the QUIT command from the AUTHORIZATION state, the POP3
session terminates but does NOT enter the UPDATE state.)

If a session terminates for some reason other than a client-issued
QUIT command, the POP3 session does NOT enter the UPDATE state and
MUST not remove any messages from the maildrop.